The present disclosure relates to a system and a method for calibrating a camera.
Recently, a market of mobile devices such as mobile phones and tablets is growing quickly. As a technical background of the rapid growth of market, the increase in the number of pixels and a pixel size of a display may be indispensably involved.
As the number of pixels of the display of a smart phone is increased, the number of pixels of an imaging camera module which is attached to a rear surface thereof is increased in proportion to the increased number of pixels.
As the number of pixels of the rear camera is increased, a demand for a market for optical image stabilization has been increased. The reason why a demand for the market of the optical image stabilization is increased is that a demand for slimness is no less strong than a demand for a high pixel. That is, despite the increase in the number of pixels, a height of the camera module is inclined to be gradually reduced rather than to be increased. To meet the tendency, the reality is that a pixel size of a sensor is getting smaller. Comparing the sensors in each generation, the pixel size of the sensor in a next generation is approximately 80% smaller than that of the previous generation like 1.75 μm→1.4 μm→1.12 μm and a pixel area of the sensor in a next generation is approximately 64% smaller than that of the sensor in the previous generation. Therefore, the area of the sensor having the pixel size of 1.12 μm is only about 40% smaller than that of the sensor having the pixel size of 1.75 μm, and thus a light quantity received by the sensor having the pixel size of 1.12 μm is also reduced to be approximately 40%. The so reduced light quantity especially increases noise at a low light level, which inevitably brings about a deterioration of image quality. To overcome the above problem, there is a need to make an exposure time of the sensor long. However, when the exposure time is increased, side effects due to handshaking are serious. That is, when the exposure time is long, a deterioration called blur occurs in the photographed image at the time of the occurrence of handshaking while the image is photographed. For the purpose of overcoming the above problem, an image stabilization technology is required. When the image stabilization technology is applied, the handshaking is calibrated during the photographing, and therefore even though the exposure time of the sensor is long, a clear image without noise may be photographed.
As the existing image stabilization technology, an actuator structure for photographing a clear image without noise as described above or an actuator driving technology has been mainly introduced.